Sizing Considerations When Buying a New Air Conditioner

October 16, 2018
By
Valley Heating, Cooling, Electrical

Share

When you’re purchasing a new cooling system, you’ll have to
make a series of choices, the first, and most important, of which should
be its size. Skipping the air conditioner sizing process could result
in a system that’s too large or too small, both of which affect
your home’s comfort in the summer and its cooling bills.

WHAT’S INVOLVED

The HVAC industry has developed software called
Manual J to accurately size HVAC systems for homes based on many factors that include:

Its cubic footage.

Levels of insulation in the attic and walls.

Number of windows, their placement, size and energy efficiency.

Orientation to the sun.

Floor plan design.

Air leakage rate.

Number of heat-producing appliances indoors.

Age and size of family.

Landscaping factors.

Each of these impacts the
energy efficiency of your home. Once all the data are entered, the software returns a value
for the recommended air conditioner sizing. The process does take time
and it involves a thorough examination and analysis of your home.

WHAT’S AT RISK

When you install an air conditioner that’s the wrong size, you risk
higher energy bills, less comfort and a shorter system lifetime. A system
that’s too big will run in short cycles, which means that it doesn’t
run long enough in each cycle to reach its optimal running speed. Energy
use will be higher because AC systems use the most power at startup.
Humidity levels will remain high because the system won’t have enough time to condense
the water vapor in the air.

Equipment that’s too small will struggle to cool your home during
extremely hot weather. Even though it’s not good, it’s better
to have a system that’s too small than too large. Humidity won’t
be an issue and the system will reach optimal running speeds most of the time.